Many stores are fitted with suspended panel ceilings which are formed of a plurality of individual rectangular tiles, each freely supported along all four edges by support members permanetly suspended from the structure. The support members are each in the shape of an inverted T, in cross-section, with the edges of the tiles resting on the horizontal flanges of the support members. Customarily, such tiles are not otherwise fixed in place and may be readily lifted above the support members to provide access to the electrical wiring and other fixed structure that is normally concealed by the tiles. The tiles are generally formed of light-weight insulating sheet material. The structural members are generally spaced approximately two feet apart in a first direction and four feet apart in a perpendicular direction to the first direction.